The present invention relates to a hard disk drive system, in particular a micro-Winchester disk drive system.
With the rapidly expanding development of personal computers and desk top data processing systems, there has been a demand for increasing the performance of the disk drive systems of such computers. The major development in this direction has been the introduction of small Winchester disk drives as replacements and enhancements to floppy disk drives for program storage. The Winchester disk drive in general provides higher capacities and faster speeds of operation, factors which are important for the effective use of personal computers running advanced software packages.
The types of Winchester disk drives that have developed in this regard were based on the use of hard disks of diameter approximately 51/4 inch, also known as mini-Winchester disks, and this so called "51/4 inch" disk drive has generally developed as an "industry standard." Such a Winchester disk drive can store typically 5-30 Megabytes of information when designed around an open-loop positioning system using a stepper motor capable of supporting up to approximately 360 data tracks per inch. However, advances made by the assignee of the present invention have expanded the storage capacity of the typical 51/4 inch disk drive up to 600 tracks per inch using this same basic type of open-loop positioning system, a track density previously believed not to be obtainable with such a stepper motor technology.
More recently, portable personal computers have been introduced, and it is clearly a performance advantage if they can achieve a high degree of software compatibility with the desk top computing systems. Portability demands special requirements on the incorporation of a hard disk system, for example, light weight, low power consumption and particularly the capability of withstanding harsher shock and vibration conditions. However, software compatibility also demands performance parameters such as data storage capability comparable to those available on 51/4 inch mini-Winchester disk drive systems.
Among the various advances that have been made in the construction and operation of disk drive systems are those developments made by the assignee of the present application, Rodime PLC, whose developments are set forth in the following U.S. patent and patent applications. The subject matter of such patent and patent applications is hereby incorporated by reference.
U.S. Pat. No. 4,392,095, entitled "Method of and Apparatus for Generating a Unique Index Mark From the Commutation Signal of a D.C. Brushless Motor" discloses a system for providing a unique index mark relative to the computer disk which is required for avoiding errors in addressing a memory location on the disk surface. This index mark is provided by correlating the commutation signal from a d.c. motor with a synchronizing signal present on one or more discrete tracks of the computer disk.
U.S. patent application Ser. No. 332,003, entitled "Read-Write Head Thermal Compensation System" discloses a thermal compensation system used by Rodime PLC in its 51/4 inch disk drive system. The positioning mechanism of this system is shown in FIG. 15 of the present application. This thermal compensation system uses different materials with different coefficients of thermal expansion for various components of the positioning mechanism for the read-write head used in the disk drive system. In the operation of this thermal compensation system, in response to a change in temperature a mispositioning of the read-write head is compensated for by a counter-movement due to the selection of various materials with different coefficients of thermal expansion within the mechanical arrangement.
U.S. patent application Ser. No. 388,165 entitled "Ventilation System for a Computer Disk Drive Hub Assembly" discloses a ventilation system for use in a computer disk drive which enables the disk file data storage capacity to be increased for a given volume of chamber housing the disk and improves the disk drive operating performance.
U.S. patent application Ser. No. 373,281 entitled "Method and Apparatus for Controlling a Stepper Motor" discloses a system for minimizing oscillations of the stepper motor for a single step, minimizing the time taken for the stepper motor to move between tracks for multi-track seek operations and reducing the angular hysteresis due to the mechanical and magnetic properties of the stepper motor construction. In controlling the operation of the stepper motor, a microprocessor circuit is adapted to drive the stepper motor in accordance with predetermined programs.